Conventionally, a light diffuser in which transparent particles are added to a thermoplastic resin has been known in the art.
However, when a common conventional light diffuser is disposed on an optical path of a light source, the light diffuser changes the color of a source light (the light emitted from the light source and reaching the eye or an illuminated object) and degrades color reproducibility of the source light. For example, if a common conventional light diffuser serving as a lighting cover is disposed on an optical path of a light source of a lighting apparatus, the light diffuser degrades color reproducibility, i.e. color rendering property, of the lighting apparatus.
PTL 1 discloses a light diffusion plate for a white fluorescent lamp cover. In order to keep the color tone of a white fluorescent lamp without a significant change when the light diffusion plate is employed as a covering material for a white fluorescent lamp of any color tone, the light diffusion plate disclosed in PTL 1 has a total light transmittance of 40% or more, with an absolute value of a difference between light transmittances at wavelengths of 436 nm and 544 nm being 5% or less, and an absolute value of a difference between light transmittances at wavelengths of 544 nm and 612 nm being 5% or less.